Pathogenesis and prognostic significance of conduction abnormalities after coronary bypass surgery.

Of 200 men who underwent isolated coronary bypass graft surgery, 40 (20%) developed new postoperative, persistent conduction abnormalities. The pathogenesis of conduction abnormalities was examined by relating their presence to that of significant proximal left coronary disease before surgery, and to various intraoperative factors that included indices of myocardial preservation and revascularization. Proximal left coronary disease was observed in 92 (46%) of 200 patients, of whom 27 (29%) developed conduction abnormalities. In contrast, of the 108 patients without proximal left coronary disease, only 13 (12%) developed persistent conduction abnormalities (P < 0.01). Intraoperative factors appeared to have little or no role in the development of such abnormalities. It is concluded that the development of persistent postoperative conduction abnormalities is related more to proximal left coronary disease than to intraoperative factors and that such abnormalities do not progress during long-term follow-up (average 53 months).